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V speeds
L) airspeed indicator with V speeds labeled]] In aviation, V-speeds or Velocity-speeds are standard terms used to define airspeeds important or useful to the operation of aircraft, such as fixed-wing aircraft, gliders, autogiros, helicopters, and dirigibles. These speeds are derived from data obtained by aircraft designers and manufacturers during flight testing and verified in most countries by government flight inspectors during aircraft type-certification testing. Using them is considered a best practice to maximize aviation safety, aircraft performance or both. The actual speeds represented by these designators are true airspeeds specific to a particular model of aircraft, and are expressed in terms of the aircraft's indicated airspeed, so that pilots may use them directly, without having to apply correction factors. In general aviation aircraft, the most commonly-used and most safety-critical airspeeds are displayed as color-coded arcs and lines located on the face of an aircraft's airspeed indicator. The lower ends of the green arc and the white arc are the stalling speed with wing flaps retracted, and stalling speed with wing flaps fully extended, respectively. These are the stalling speeds for the aircraft at its maximum weight. Having V speeds properly displayed is an airworthiness requirement for type-certificated aircraft in most parts of the world. Regulation The most common V-speeds are often defined by a particular government's aviation regulations. In the United States, these are defined in title 14 of the United States Code of Federal Regulations, known as the Federal Aviation Regulations or FARs. In Canada, the regulatory body, Transport Canada, defines 26 commonly-used V-speeds in their Aeronautical Information Manual (AIM). Regulatory V-speeds These V-speeds are defined by regulations. Other V-speeds Some of these V-speeds are specific to particular types of aircraft and are not defined by regulations. Mach Numbers Whenever a limiting speed is expressed in terms of Mach Number, it is expressed as an 'M speed', e.g. VMO: Maximum operating limit speed (in knots), MMO: Maximum operating limit Mach. V1 definitions V1 is the critical engine failure recognition speed or takeoff decision speed. It is the decision speed nominated by the pilot which satisfies all safety rules, and above which the takeoff will continue even if an engine fails. The speed will vary between aircraft types and also due to aircraft weight, runway length, wing flap setting, engine thrust used, runway surface contamination and other factors. V1 is defined differently in different jurisdictions: *The US Federal Aviation Administration defines it as: V1 means the maximum speed in the takeoff at which the pilot must take the first action (e.g., apply brakes, reduce thrust, deploy speed brakes) to stop the airplane within the accelerate-stop distance. V1 also means the minimum speed in the takeoff, following a failure of the critical engine at VEF, at which the pilot can continue the takeoff and achieve the required height above the takeoff surface within the takeoff distance. *Transport Canada defines it as: Critical engine failure recognition speed and adds: This definition is not restrictive. An operator may adopt any other definition outlined in the aircraft flight manual (AFM) of TC type-approved aircraft as long as such definition does not compromise operational safety of the aircraft. References Category:Aircraft instruments Category:Airspeed Category:Aviation terminology es:Velocidades características fr:Vitesse aéronautique he:מהירויות-V nl:V-snelheden sv:V2 (hastighet) zh:V速度